An aircraft carrier is a warship that serves as a seagoing airbase, equipped with a full-length flight deck and facilities for carrying, arming, deploying, and recovering aircraft.[1] Typically, it is the capital ship of a fleet, as it allows a naval force to projectair power worldwide without depending on local bases for staging aircraft operations. Carriers have evolved since their inception in the early twentieth century from wooden vessels used to deploy balloons to nuclear-powered warships that carry numerous fighter planes, strike aircraft, helicopters, and other types of aircraft. Whilst heavier aircraft such as fixed-wing gunships and bombers have been launched from aircraft carriers, it is currently not possible to land them. By its diplomatic and tactical power, its mobility, its autonomy and the variety of its means, the aircraft carrier is often the centerpiece of modern combat fleets. Tactically or even strategically, it replaced the battleship in the role of flagship of a fleet. One of its great advantages is that, by sailing in international waters, it does not interfere with any territorial sovereignty and thus obviates the need for overflight authorizations from third party countries, reduce the times and transit distances of aircraft and therefore significantly increase the time of availability on the combat zone.

There is no single definition of an "aircraft carrier,"[2] and modern navies use several variants of the type. These variants are sometimes categorized as sub-types of aircraft carriers,[3] and sometimes as distinct types of naval aviation-capable ships.[2][4] Aircraft carriers may be classified according to the type of aircraft they carry and their operational assignments. Admiral Sir Mark Stanhope, RN, former First Sea Lord (head) of the British Royal Navy, has said, "To put it simply, countries that aspire to strategic international influence have aircraft carriers".[5]Henry Kissinger, while United States Secretary of State, also said: "An aircraft carrier is 100,000 tons of diplomacy".[6]

As of August 2018, there are 41 active aircraft carriers in the world operated by thirteen navies. The United States Navy has 11 large nuclear-powered fleet carriers—carrying around 80 fighter jets each—the largest carriers in the world; the total combined deckspace is over twice that of all other nations combined.[7] As well as the aircraft carrier fleet, the U.S. Navy has nine amphibious assault ships used primarily for helicopters, although these also carry up to 20 vertical or short take-off and landing (V/STOL) fighter jets and are similar in size to medium-sized fleet carriers. China, France, India, Russia, and the UK each operate a single large/medium-size carrier, with capacity from 30 to 60 fighter jets. Italy operates two light fleet carriers and Spain operates one. Helicopter carriers are operated by Australia (2), Brazil (1), Egypt (2), France (3), Japan (4), South Korea (1), and Thailand (1). Future aircraft carriers are under construction or in planning by Brazil, China, India, Russia, the United Kingdom, and the United States.

(note: some of the types listed here are not strictly defined as aircraft carriers by some sources)

By role

A fleet carrier is intended to operate with the main fleet and usually provides an offensive capability. These are the largest carriers capable of fast speeds. By comparison, escort carriers were developed to provide defense for convoys of ships. They were smaller and slower with lower numbers of aircraft carried. Most were built from mercantile hulls or, in the case of merchant aircraft carriers, were bulk cargo ships with a flight deck added on top. Light aircraft carriers were fast enough to operate with the main fleet but of smaller size with reduced aircraft capacity. Soviet aircraft carriers now in use by Russia are actually called heavy aviation cruisers; these ships, while sized in the range of large fleet carriers, were designed to deploy alone or with escorts, and provide both strong defensive weaponry and heavy offensive missiles equivalent to a guided missile cruiser, in addition to supporting fighters and helicopters.

By configuration

Aircraft carriers today are usually divided into the following four categories based on the way that aircraft take off and land:

Catapult-assisted take-off barrier arrested-recovery (CATOBAR): these carriers generally carry the largest, heaviest, and most heavily armed aircraft, although smaller CATOBAR carriers may have other limitations (weight capacity of aircraft elevator, etc.). All CATOBAR carriers in service today are nuclear powered. Two nations currently operate carriers of this type: ten Nimitz class and one Gerald R. Ford class fleet carriers by the United States, and one medium-sized carrier by France, for a world total of twelve in service.

Short take-off but arrested-recovery (STOBAR): these carriers are generally limited to carrying lighter fixed-wing aircraft with more limited payloads. STOBAR carrier air wings, such as the Sukhoi Su-33 and future Mikoyan MiG-29K wings of Admiral Kuznetsov are often geared primarily towards air superiority and fleet defense roles rather than strike/power projection tasks,[citation needed] which require heavier payloads (bombs and air-to-ground missiles). Today China, India, and Russia each operate one carrier of this type – a total of three in service currently.

Short take-off vertical-landing (STOVL): limited to carrying STOVL aircraft. STOVL aircraft, such as the Harrier Jump Jet family and Yakovlev Yak-38 generally have limited payloads, lower performance, and high fuel consumption when compared with conventional fixed-wing aircraft; however, a new generation of STOVL aircraft, currently consisting of the F-35B, has much improved performance. The US has nine STOVL amphibious assault ships. The UK has a class of two 65,000 ton[9] STOVL aircraft carriers, HMS Queen Elizabeth and HMS Prince of Wales, the largest warships ever built for the Royal Navy; with one in service and the other being fitted out. Italy operates two in the light fleet role, and Spain operates one amphibious assault ship as a STOVL aircraft carrier, giving a total of thirteen STOVL carriers in active service; (Thailand has one active STOVL carrier but it no longer has any operational STOVL aircraft in inventory so is used and counted as a helicopter carrier).

Helicopter carrier: Helicopter carriers have a similar appearance to other aircraft carriers but operate only helicopters – those that mainly operate helicopters but can also operate fixed-wing aircraft are known as STOVL carriers (see above). There are currently fourteen helicopter carriers (that solely operate helicopters and not fixed-wing aircraft), operated by seven navies, in commission today. Japan has four of this type, France three, Australia two, Egypt two, and South Korea, Thailand, and Brazil have one each. In the past, some conventional carriers were converted and called commando carriers by the Royal Navy. Some helicopter carriers, but not all, are classified as amphibious assault ships, tasked with landing and supporting ground forces on enemy territory.

By size

The Japanese carrier Shinano was the biggest carrier in World War II, and the largest ship destroyed by a submarine.[10]

Supercarrier

The appellation "supercarrier" is not an official designation with any national navy, but a term used predominantly by the media and typically when reporting on new and upcoming aircraft carrier types. It is also used when comparing carriers of various sizes and capabilities, both current and past. It was first used by The New York Times in 1938,[11] in an article about the Royal Navy's HMS Ark Royal, that had a length of 209 metres (686 ft), a displacement of 22,000 tonnes and was designed to carry 72 aircraft.[12][13] Since then, aircraft carriers have consistently grown in size, both in length and displacement, as well as improved capabilities; in defense, sensors, electronic warfare, propulsion, range, launch and recovery systems, number and types of aircraft carried and number of sorties flown per day.

While the current classes in service, or planned, with the navies of China, India, Russia, and the UK, have displacements ranging from 65,000[9] to 85,000 tonnes,[14] lengths ranging from 280 meters (920 ft)[15] to 320 meters (1,050 ft)[16] and varying capabilities, have been described as "supercarriers",[17][18][19][14] the largest "supercarriers" currently in service are with the US Navy,[20] with displacements exceeding 100,000 tonnes,[20] lengths of over 337 meters (1,106 ft),[20] and capabilities that match or exceed that of any other class.[21][22][23][24][25]